A beverage holder having an adjustable mounting system includes a cylindrical-shaped cup member and a clamp assembly which are secured together using a threaded fastening member. The cup member has a recessed portion offset outwardly from the sidewall, and a slotted opening formed in the recessed portion which extends along a length of the cup member. The fastening member extends through the slotted opening and into a corresponding opening in the clamp assembly. The fastening member is arranged to slide along the slotted opening for vertical adjustment of the cup member relative to the clamp member. The fastening member also allows the cup member to be pivotally adjusted relative to the clamp assembly to adapt to different angles of bars on which the beverage holder is mounted. The cup member has a cutaway portion that allows access to the fastening member and accommodates a handle of a beverage container.